1. Field Of The Invention
This invention concerns an improved apparatus and method for jacking and dollying a vehicle wheel assembly, while the assembly remains affixed to the vehicle, the wheel assembly including a pneumatic tire, a wheel and an axle; and more particularly, a jacking an dollying apparatus having wheel assembly engaging elements and an actuator, wherein the wheel assembly engaging elements include one or more roller assemblies, and the actuator includes a bi-directional, double pawl, lever ratchet mechanism, and wherein the method includes steps for successively driving the wheel assembly engaging elements against the tire to lift the wheel assembly by alternate leveraged driving and bracing of members which couple the wheel assembly engaging elements, and steps for permitting the wheel assembly to successively repulse the wheel assembly engaging elements to lower the wheel assembly by alternate leveraged releasing and resetting of the bracing between members which couple the wheel assembly engaging elements.
2. Description of Related Art
As pointed out in my U.S. Pat. No. 4,690,605, issued Sept. 1, 1987, entitled "Apparatus For Jacking And Dollying An Affixed Vehicle Wheel Assembly", movement of conventional vehicles in confined spaces such as found in repair garages, body shops, and parking facilities, is difficult at best, and can be impossible altogether.
The movement difficulties associated with front wheel steering arise from its inherent limitations. As all drivers have found, front wheel steering permits vehicle movement in only straight line and relatively broad arcuate paths. As a result, where right angle, rotational or shallow arcuate paths are required, movement may not be possible unless sufficient space exists within which to approximate such paths with a series of straight line and broad arc maneuvers.
Meeting such space requirements, however, can create problems. In commercial settings such as garages, body shops and parking facilities, providing sufficient space to accommodate front wheel steering may require servicing fewer vehicles, increasing floor space, or some combination of the two. But accommodating fewer vehicles and providing larger space adversely affects economics. They entail either loss of operating revenue due to the reduced number or vehicles served or additional capital outlay for construction of increased space. Further, even in non-commercial settings, space limitations and economics may prohibit accommodation of the number of vehicles of choice.
However, as described in my above referenced patent, if a vehicle where free to swivel about its vertical axis; as for example, where the vehicle where mounted on a dolly, the limitations of front wheel steering could be overcome and the economics of vehicle accommodation substantially improved.
But, the complexity of providing a suitable dolly, and the loading and unloading of a vehicle to and from it is not insignificant. Such a dolly would have to have a capacity sufficient to sustain the size and weight of the vehicle. Accordingly, the device would be expected to have a costly and bulky construction. Additionally, means would have to be provided for lifting the vehicle from the ground onto the dolly, and from the dolly back to the ground again, adding further cost and complexity.
As also pointed out in my above noted patent, an alternative to lifting the entire vehicle onto a single dolly would be to use individual jacking and dollying units placed at each vehicle wheel assembly. Use of individual units capable of both lifting the wheel assembly and carrying it while affixed would permit each wheel assembly to be raised from the ground, and once raised, effectively swiveled by means of casters provided on the unit.
Further, use of individual wheel jacking and dollying units would have the added advantage of permitting movement of vehicles immobilized because of one or more disabled wheel assemblies. Where a broken or damaged assembly has immobilized the vehicle, the vehicle could be made movable again by mounting the disabled assembly on an individual dolly unit, the action of the units casters being substituted for the disabled wheel assembly.
While in the past, wheel jacking and dollying devices have been proposed, some for transporting wheel assemblies while the assembly remains affixed to the vehicle, and, others for, more simply, removing a wheel and tire from a vehicle and, thereafter, transporting the removed wheel and tire, both types have lacked the ease of use and simplicity of construction to render them attractive, especially for commercial use.
More particularly, devices have been proposed for removing vehicle wheels and tires from a vehicle axle, and transporting them once removed. These devices were intended to facilitate tire and wheel replacement where the tires or wheels were worn, damaged or flat, and too large and heavy to be conveniently replaced by hand; for example, tires and wheels of trucks and buses.
However, these devices are limited. In operation, they require use of an auxiliary jack to first lift the vehicle to remove the vehicle weight from the wheel assembly. Thereafter, the device is positioned beneath the tire and wheel so tire and wheel can be taken off and transported away. What jacking ability they have is directed to lifting the tire and wheel form the already raised and supported axle. The wheel engaging elements and actuator mechanism they feature are not intended to provide a mechanical advantage suitable for lifting the entire vehicle.
But, use of a separate jack to first lift and support the vehicle is unattractive. It requires extra time and effort to first position 80 and actuate the auxiliary jack, and there is the added cost of the auxiliary jack itself.
As a further drawback, these devices tend to have awkward and slow acting mechanisms which do not provide simple and convenient operation. Further, they typically have a size and shape that would encumber movement if the vehicle could be moved once on the device.
An example of such a device is given in U.S. Pat. No. 2,380,415, issued July 31, 1945, to E. R. Carruthers. In his patent, Carruthers describes a tire and wheel dolly intended to handle the dual rear wheels of a truck. In accordance with his design, a separate jack is needed to lift the truck axle, wheel and tires from the ground so that the apparatus can be rolled beneath. Thereafter, cradles provided on the apparatus are brought beneath and against the tires by means of a crank and screw mechanism, to lift the tires and wheels from the supported axle. Accordingly, the Carruthers apparatus requires the undesirable step of and equipment for separately lifting the wheel assembly before the apparatus can be used. Further, because of the crank and screw actuator mechanism, the Carruthers design is not susceptible of quick, simple manipulation.
Other and similar examples of tire and wheel dollies are found in U.S. Pat. Nos. 1,967,119; 2,170,607; 2,217,898; 2,386,516; 2,410,902; and 3,836,027. However, as in the case of the Carruthers apparatus, a separate jack is required to first lift and support the vehicle. Yet further, the bulk and complexity of these devices would encumber vehicle movement if the vehicle could be sustained on the device, and their actuator mechanisms are not suited to simple and quick operation.
A tire and wheel dolly of the above described type featuring a simplified construction, however, has been proposed in French patent No. 2,419,177 issued to Jean-Pierre Jacques, and published Oct. 5, 1979. In accordance with the Jacques design, a manually operable lever mechanism is arranged to drive rollers against the tread face on opposite sides of a tire to be lifted. As the rollers are forced against the tread, the tire is caused to ride onto the rollers and be lifted from the vehicle axle.
But, as with the previously described devices, the Jacques apparatus calls for use of a separate jack to first lift the vehicle axle. Further, in the case of the Jacques apparatus, the rudimentary nature of the lever mechanism and the action of the rollers render use of a separate jack even more necessary. Because of the roller pincer action, the apparatus must provide sufficient force to both lift the wheel and tire, and, overcome drag resistance of the tire to the rollers. While drag is typically not significant where the tire is unloaded, deformation of the tire in the presence of the vehicle weight; e.g., if the auxiliary jack is not used, does render drag significant, and a problem where the pneumatic tire is under inflated. Accordingly, the Jacques apparatus not only exhibits the cost and operating disadvantages associated with use of an auxiliary jack, but also, the potential further problem of required additional mechanical advantage to overcome the effect of tire drag resistance.
As noted, other devices have been proposed for jacking and dollying affixed wheel assemblies, and are able to do so without the aid of an auxiliary jack. But, these devices require use of slow acting and complicated actuator mechanism to accomplish lifting, and for this reason are also unattractive.
More particularly, in U.S. Pat. No. 2,362,981, C. P. Baum proposes an apparatus for parking airplanes. The apparatus features, in several embodiments, wheel engaging elements and various crank and lever actuators for lifting and supporting an aircraft wheel assembly. The design of the wheel engaging elements and actuator mechanisms, however, call for complicated and costly construction, and require awkward manipulation in operation. Thus the device is unsuited for usage where low manufacturing cost and simple operation are desired.
Finally, while a more conveniently operated apparatus has been proposed for transporting affixed vehicle wheel assemblies, the apparatus has been provided with adequate lift capacity and made more convenient to operate at the cost of rendering the actuator mechanism even more complicated and expensive than the previous, all mechanical designs.
In U.S. Pat. No. 3,954,198, F. X. Sedelmeyer describes a lift truck for raising vehicle wheel assemblies to permit vehicle movement in confined spaces or towing in the case where the wheel assembly is jammed. The Sedelmeyer apparatus features rollers mounted on a telescoping framework that is actuated by a multi-piston, multi-chambered hydraulic system. In accordance with the Sedelmeyer design, manual manipulation of the hydraulic pump associated with the framework causes the rollers to be driven against the wheel assembly tire, to thereby lift the assembly.
While the Sedelmeyer hydraulic pump is able to provide adequate lift capacity and convenient operation, the complexity of the pump mechanism with its multiple pistons, chambers and valves, renders the apparatus costly to manufacture. Additionally, because the apparatus is hydraulic, it is subject to leakage and slippage, aspect which further detract from its desirability.